The roller wheels of a roller wheel assembly are typically, in use, arranged to roll along a metal track, having a specific path for each roller wheel of the pair of roller wheels. Sometimes, multiple pairs of roller wheels may be provided in particular assemblies. Such assemblies are often used as an elevated rolling support for doors, windows and the like including but not limited to cavity door rolling supports. Other applications may include a variety of conveyors, particularly overhead conveyors. There are a number of known methods for mounting the bearing in the body of the carriage member including making the carriage member body in two or more parts that are connected by fasteners around the bearing, directly moulding a plastics material body about the bearing (or bearings), and press fitting the bearing in an axial direction into a purpose formed cavity for the bearing. Such arrangements are usually characterized by the outer peripheral surface of the bearing being fully supported by the body of the carriage member. Such known arrangements, while working satisfactory, have a number of disadvantages including the difficulty of the assembly process and the costs of the material required for the body of the carriage member. All these have an adverse affect on the costs of roller wheel assembly over all. The objective of the present invention is to provide an improved structure for a carriage member body for mounting at least one bearing thereto for use in a roller wheel assembly of the above discussed type.